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Mamma Mia!! It's Another Grimac

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  • Mamma Mia!! It's Another Grimac

    My Grimac 2-group has a little sister.
    A one-group Grimac Mia. Click image for larger version

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    They look good side by side. But the solid Tasmanian Oak benchtop is struggling under their considerable combined weight.
    Click image for larger version

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    Something I'll have to address very soon.

    Of course they can't fire up simultaneously, not without some household rewiring. But it's nice to have a choice.

    Big Grimac needs a good hour to warm up. Mia about half an hour.

  • #2
    Well done, Robusto!

    Was it Plato or Confucius who was credited with saying "One can never have too many espresso machines!" ???

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    • #3
      Oh nice look. One can never have too many Grimacs is what I always say!

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      • #4
        The Mia is by no means a "half version" of its two-group big brother. They share a robust build and same E-61 group, and the steam valves and auto fill sensors look alike. But that's where it ends.

        Boiler is 1.3L vs 4.9L. Vibe pump vs rotary. Mater vs big Sirai pressurestat (but it IS silent). Tank vs plumbed. 1300 watt boiler vs 2600-3300. Touch pads, boiler safety valves, vacuum break valves all different. Simple on-off switch vs massive rotary. No water level sight glass. Tiny-ish drip tray. No emergency brew switch. No brew pressure gauge.

        But I love it.

        Leaving it idle, it's silent. No regular clicking of the pressurestat. Just the quiet gurgle of the boiler for a couple of seconds as the pressurestat kicks in.

        The one-hole steam tip is a little slow, so I will probably order a twin. And despite early reservations I like the touch pad controlled water tap.

        Does it make a mean espresso? Too early to tell. I ran out of my home-roasted beans and bought 200 grams of sacrificial month-old passable Daley St beans from Coles. (Only bought because they had a roasted on as well as a best before date)

        Tried my 4-day old Yirg and Brazil bourbon blend beans this morning. 20 grams in, 37 grams out.

        Great mouthfeel. Very viscous, unctuous. The way I like it. But awful taste. Need more degassing. And/or temperature control. Or both.

        Cooling/ heating flushes, I've no idea. Yet.

        So a lot of learning ahead of me. Pity I can't have both machines running simultaneously for quick direct comparisons of brews



        Comment


        • amberale
          amberale commented
          Editing a comment
          How about a heavy duty extension cord to an outlet on a different circuit just for the comparison?

      • #5
        Amberale, great idea. Thanks. Tomorrow I'll check to see whether the power points have separate circuits/breakers and if so try out your idea. Mia is only 1300 watts, so about 5 amps, well inside the 10 amp capacity of ordinary extension cords.

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        • #6
          Been very busy. I haven't done the comparison between Mia and Grimac 2-group yet. And I keep running out of beans.

          I did test the breakers though, and unfortunately all nearby kitchen power point's are on the same circuit. So it's going to be a very long extension cord across the kitchen for the test only.



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          • #7
            I've been brewing some very nice ristrettos on both Mia and it's elder brother, the Grimac 2-group. Yesterday morning I suddenly decided to remove the mushroom and take a peek inside. The previous owner assured me he had regularly descaled the machine with a proprietary solution. But when the mushroom came out, there was a somewhat surprising amount of limescale. Not enough to cover it completely, but it wasn't pristine either for something which is supposedly regularly descaled and has a water softener cartridge in the tank.

            So I descaled it, made sure all the holes were clear, including the tiny gicleur, and put put the mushroom back in.

            However, the vibe pump decided that while it would run, it wouldn't suck water.

            That sparked a couple of hours of fun, standing on a small ladder, forcing through water into the silicone hose intake with a small syringe, then holding the hose end and the softener cartridge underwater and blindly attaching one to the other.

            Finally, it started sucking...but no water was emerging from the group.

            I don't know how many times I removed and replaced that mushroom. Made sure water was reaching it --it was. Removed and reinstalled the solenoid. Nothing.


            After about 8 hours I gave it away and tried to watch some TV...and although it was almost 9 PM, I returned, removed the mushroom again, and this time, not only the solenoid, but the three-way valve as well over which the solenoid sits.

            Well, no wonder I couldn't poke a wooden barbecue skewer all the way through. The tiny, pin-size hole in that valve was absolutely packed with white scale.

            It was such a relief to see, after 10 hours or more of work, because it identified the problem.

            I don't know whether having loosened scale from the mushroom made it accumulate there under pressure, or whether it was waiting to happen yesterday. I suppose the blocking created an air pocket for the water circuit which the pump couldn't overcome?

            Anyway, put everything back together and everything is working as it should.

            It's satisfying when something like that can be fixed without buying any parts.

            Comment


            • tompoland
              tompoland commented
              Editing a comment
              my goodness, full marks for pesistence and congrats on the breakthrough, literally (the pin sized hole), I'll bet you slept better than you would have if you quit.

          • #8
            Oh yes. Like I said, never give up. My wife's car entry fob for my car stopped working months ago. I've spent hours going over it, put it away, come back to it in a week etc...finally got it working yesterday!

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            • #9
              I've got an Inkbird BBQ thermo-pen that dies on me every six months.
              It is a soldered wire attached to a swiveling joint.
              I really need to replace the wire with an upgrade but at this stage it is three screws and 5 minutes with the soldering iron rather than $250 for a new one.

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              • #10
                I hate working in the dark when all around exists the technology to light up my life. The 2-group Grimac had gauges to tell me boiler and water pressure. But not temperature. Last year I fixed that by installing thermocouples, one in each group, and digital displays. Happiness.

                But Grimac Mia has one gauge only, for boiler pressure. So I borrowed one of the thermometers from its big brother, put a thermocouple in its group...and made a startling discovery.

                ignorance was bliss. I was enjoying nice ristrettos. Little did I know they were being extracted at 85 to 86 degrees. And for lighter roasts too.

                pressurestat was showing 1.2 to 1.4 bar, so lenty of boiler heat in the single boiler 1.2 Litres HX.

                Incredulous, I double checked with another thermocouple. Same result. Stuck another thermocouple up a portafilter spout to measure emerging water, and it pretty near matched whatever the one in the group head displayed.

                Another blockage? Mushroom checked OK. The lower end was clear too.

                Another suspect area was the restrictor in the upper pipe from heat exchanger to grouphead. I'd left that alone before because I struggled to unscrew the pipe from the group. But with a very large shifter and brute force this time it was persuaded to yield.

                And sure enough, the toothpick-size hole in the restrictor was caked up. Cleaned it, put the pipe back, and joyously watched the temperature pass the 86 degrees C barrier to 92-93C. Happiness.

                But the worrying thing remains... what's it say about my taste buds, having enjoyed ristrettos in the mid-80s degrees ?








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                • #11
                  what's it say about my taste buds, having enjoyed ristrettos in the mid-80s degrees
                  Must be down to the wonderful job you do roasting your coffee Robusto...
                  Imagine what's ahead of you.

                  Mal.

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                  • #12
                    Mal, you're too generous, but thanks

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                    • #13
                      Just some trivia for those Interested in machine power consumption.

                      Grimac Mia is a single boiler HX machine, with a 1.2 litre boiler, water tank, and rated at 1300 Watts.

                      Yesterday I had it on continuously from 7 am to 12 pm. Five hours. According to the nifty grid connect wifi powerpoint, it consumed 0.99 kWh of electricity. About 35 cents, or 7 cents per hour.

                      Here's a screenshot.Click image for larger version

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